In communication networks, there is always a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communication network is deployed.
As an example, the standardization organization the 3rd Generation Partnership Project (3GPP) specifies the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) technology consisting of two duplex modes; frequency-division duplexing (FDD) and time-division duplexing TDD. UTRA-FDD is also denoted Wideband Code Division Multiple Access (WCDMA), and UTRA-TDD is also denoted Time Division Synchronous Code Division Multiple Access (TD-SCDMA).
In general terms, the UTRA-FDD mode has been widely deployed globally whereas the UTRA-TDD mode is only deployed in one country and one operator in the world, i.e. China and the China Mobile Communications Corporation (CMCC). The China Communications Standards Association (CCSA) has published its own version of the UTRA specifications. This version differs from the 3GPP version and for the protocol layer three radio resource control (L3 RRC) message specification done in the Abstract Syntax Notation One (ASN.1) syntax the two specifications (i.e., as provided by 3GPP and CCSA) are not compatible. This may cause a situation in a wireless terminal which is configured to support both UTRA-FDD and UTRA-TDD in parallel since two different specifications for the ASN.1 must be used. The specification for the ASN.1 to be use is determined by the UTRA duplex mode.
An incorrect ASN.1 version usage will corrupt the communication with the radio base stations in the communication network. One issue concerns the selection of the correct ASN.1 specification, especially when both UTRA-FDD and UTRA-TDD are enabled and none of them are the controlling or active radio access technology (RAT) of the wireless terminal. For these cases the controlling or active RAT could be for example one of the Global System for Mobile Communications (GSM), the Long Term Evolution (LTE) wireless standard or the CDMA2000 standard.
Hence, there is a need for improved determination of network environment for a wireless terminal.